The present invention relates to an information search apparatus and method for searching information on the basis of an input query word.
A conventional information search apparatus, which searches multimedia information, e.g., image information, makes a search using data (keywords) derived from subjective evaluation results of one or a plurality of persons for images to be searched, physical image features extracted from images, and the like.
Also, an image search apparatus that obtains a required image by matching a given keyword with that corresponding to an image has been realized. Furthermore, an information search apparatus, which obtains an image, that cannot be obtained by full-word matching with an input keyword, by matching not only the input keyword but also an associated keyword associated with the input keyword with a keyword corresponding to an image, has also been realized. Moreover, an information search apparatus which obtains an image with similar color information by detecting a correspondence between the input keyword and color information using, e.g., color information of images is proposed.
For example, in one scheme, an impression that a person receives upon watching an image, or key information linked with the impression is appended to image information and is used in search. As the key information, words that express impressions evoked by images such as “warm”, “cold”, and the like, and words that represent objects in drawn images such as “kitty”, “sea”, “mountain”, and the like are appended as keywords. Also, local image feature components on drawn images are subjectively evaluated and are often appended as key information. For example, information that pertains to a color such as “red”, “blue”, and the like, information that pertains to a shape such as “round”, “triangular”, “sharp”, and the like, and information that pertains to a texture such as “sandy”, “smooth”, and the like are expressed using words and icons, are appended to images as key information, and are used in search.
In another system, physical image feature amounts are extracted from images, and are used in image search. Image features include local colors painted on images, overall color tones, and shapes, compositions, textures, and the like of objects on drawn images. An image feature amount is extracted from segmented regions or blocks obtained by segmenting the overall image into regions based on color information, or segmenting the image into blocks each having a given area, or is extracted from the entire image. Physical image features include, e.g., color information, density distribution, texture, edge, region, area, position, frequency distribution, and the like of an image.
However, in the prior art, when an image including a keyword that matches the input query word is searched for, images which do not match the search request of the searcher are often obtained. Especially, when an image search is made using an abstract query word such as a “refreshing” image, images found by the search are limited. To solve this problem, a search may be made by unfolding the query word “refreshing” to keywords which are associated with that query word. However, when such scheme is used, images which are not “refreshing” may be mixed in search results.
In place of query words, a query image may be input, and a search may be made using the feature amount of the input image. In this case, a query image that reflects the searcher's will must be prepared, and it is difficult to select a query image, resulting in poor operability.